An Internet Protocol (IP) Multimedia Core Network Subsystem (IMS) is a next-generation network standard defined by the 3rd Generation Partnership Project (3GPP). The IMS may encapsulate a conventional voice service into an IP data packet for end-to-end transmission. An increasingly mature Long Term Evolution (LTE) technology, as a transmission link, may also acquire a relatively higher transmission rate and a relatively lower delay. Therefore, an LTE-system-based IMS service emerges.
At present, in an LTE-system-based IMS service, a large number of resources are required to be consumed for data encryption and decryption. Therefore, in a communication scenario with a low security requirement, such as a basic civil communication and a broadcast service, data of an air interface is transmitted without encryption, and there is no protection provided for a transmitted IP data packet.
Therefore, a terminal may easily access an illegal evolved Node B. As such the illegal evolved Node B may acquire private information of the terminal through a Dedicated Control Channel (DCCH), such as an International Mobile Subscriber Identification Number (IMSI) and International Mobile Apparatus Identity (IMEI) information of the terminal. Furthermore, the illegal evolved Node B may send risky downlink data to the terminal through a Dedicated Traffic Channel (DTCH), such as a junk short message, Trojan planting and permission tampering. Therefore, a risk of the IMS terminal in a re-establishing of the radio resource(s) process is increased.